ICT Project Combines Weather Data and Computer Models to Help IDOT Highway Maintenance Crews Keep Illinois Roads Clear

Obtaining an accurate picture of road conditions at any given time is a great benefit to motorists and road construction and maintenance crews. Currently, highway maintainers use weather forecast sites and road weather information system (RWIS) data to support winter maintenance decisions. Combining weather forecast data with pavement models creates a new dataset that can be highly useful to IDOT, as well as to municipal and county agencies.


Real weather and pavement data become a simulation of road conditions throughout the state.

This was the motivation for the recent study, “Evaluation of Software Simulation of Road Weather Information System” (ICT Project R27-142), a collaboration between IDOT and ICT, which was a project designed to use the Enhanced Integrated Climatic Model (EICM) to turn data collected by IDOT’s RWIS into information that people in the field could use.

EICM is a computer model of heat and moisture flow in pavements first developed by ICT’s first director, Barry Dempsey, over 40 years ago and continually improved since. As principal investigator Bill Vavrik of Applied Research Associates (ARA) states, “This project allows those decades of model development and improvement to have an impact on snow and ice control on Illinois roads and other roads across North America. This is an exciting project because of its history, its current uses, and the ability to bridge that technology to the future.”

A traditional RWIS is a data collection system with stations all over the state that use sensors to collect data about weather and road conditions. Maintaining these stations so that they provide complete and accurate information has proven difficult and expensive. The challenge for this project was to collect measured RWIS road condition data for comparisons to the model predictions, and then to ensure that the model could give accurate results.

“The data,” Vavrik states, “was delivered as millions of small data files that needed to be processed to a usable form.” Vavrik and his coworkers also had to scour for pavement property data for all interstate highways in Illinois. In the end they were able to model 217 virtual roadway weather stations across Illinois and compare EICM’s predictions with actual data collected by RWIS. They found the model gave reasonable predictions of surface temperature, as they had hoped.

As Technical Review Panel chair Derek Parish of IDOT states, district Operations personnel will be able to “predict pavement freezing in order to more efficiently use limited resources, such as overtime hours and salt.” Looking forward, he says IDOT plans to “provide training sessions to show Operations personnel how the virtual road weather stations’ website can be used to assist with planning.” This means large sets of data that researchers have been collecting will now be in a form useful to IDOT staff operating in the field.

Potential next steps in this work include adding details about rain and snow to the model. Vavrik notes that “the model does not have a heat transfer function that relates to the temperature of rain/snow” and that this future improvement would give agencies an even better tool for predicting road conditions in a variety of weather events.

Originally Published 10/25/2016